Hydrocarbon lubricant containing sulfurized aliphatic borates as stabilizers



Patented Oct. 17, 1950 HYDBOCARBON LUBRICANT CONTAINING SULFURIZED ALIPHATIC BOBATES AS STABILIZERS Dilworth T. Rogers, Summit, and John G. McNab, Cranford, N. J., assignors to Standard Oil De-' c velopment Company, a corporation oi Delaware No Drawing.

Application October 29, 1947 Serial No. 782,954

11 Claims. (01. 252-4s.3)-

This invention relates to the improvement of hydrocarbon products derived from petroleum sources and more particularly to the preparation of improved mineral lubricating compositions by the incorporation therein of a class of additives which impart oxidation resisting properties thereto.

In the development of petroleum lubricating oils the trend has been to use more and more emclent refining methods in order to reduce the tendency of the oils to form carbon and deposits of solid matter or sludge. While such highly refined oils possess many advantages, resistance to oxidation, particularly under conditions of severe service, is generally decreased and they are more prone to form soluble acidic oxidation products which are corrosive. They are generally less efiective than the less highly refined oils in protecting metal surfaces which they contact against rusting and corrosion due to oxygen and moisture. Although generally superior to lightly refined oils, under severe conditions they may tend to deposit thick films of "varnish" on hot metal surfaces, such as the pistons of internal combustion engines.

In accordance with the present invention a new class of compounds has been discovered which when added to refined lubricating oils and other petroleum hydrocarbon products in small proportions substantially reduces the' tendency of such oils to corrode the metal surfaces, particularly thesuriaces of copper-lead and cadmium-silver bearings which are employed in some internal combustion engines, and

they are likewise effective in inhibiting oxidation of petroleum hydrocarbon products generally. These compounds also impart oiliness properties to mineral lubricating oils when employed in substantial amounts.

The new class of materials which have been found to possess the antioxidant and stabilizing properties described above are esters of boric acid in which the organic radical is a sulfurized aliphatic hydrocarbon radical containing at least five carbon atoms. Esters of this type may be used in which one, two or three of the hydrogen atoms of boric acid are replaced by the specified organic radicals. These esters may be formed by reacting boric acid with a sulfurized aliphatic alcohol, or they may be formed by first reacting boric acid with an unsaturated alcohol and then sulfiu'izing the ester so formed.

The alcohols which may be employed as starting materials in forming the sulfurized esters of the present invention include any of the unsaturated monohydric aliphatic alcohols containing at least five carbon atoms per molecule, which may have straight or branched carbon chains. Examples of such alcohols are the pentenols, hexenols, octenols, citronellol, undecenol, oleyl alcohol, and the like. These alcohols may be sulfurized by heating with sulfur. usually at temperatures in the neighborhood of 300 F. The sulfuri'zed alcohol may be readily reacted with boric acid by heating in the presence of. any convenient solvent and 1 water remover, such as benzene, naphtha, or the like, for a sufflcient time to complete the reaction, which can be conveniently determined by measuring the water formed in the reaction, which may be trapped out by convenient means. When the theoretical amount'of water corresponding to the completed reaction has been formed the heating process is discontinued and the solvent evaporated from the product. No catalyst is required in the esterification reaction. Temperatures of to 300 F. are generally required.

When employed for the purpose of inhibiting oxidation and corrosive tendencies in mineral lubricating oils and other hydrocarbon products they are generally employed in proportions ranging from about 0.01% to 3.0% by weight, while for the purpose of imparting oiliness prop erties to mineral lubricating oils theywill normally be used in somewhat larger quantities, i. e. of the order of 3% to 10%. These amounts will vary according to the base material in which they are employed and in accordance with the requirements for particular applications.

' The following examples illustrate the preparation and testingof the new compounds of the present invention, but it is to be understood that these examples do not limit the scope of the invention in any manner.

Example 1.- Preparation of sulfurized oley alcohol Example 2.--Preparation of tri-(suljflried oleyl) borate 20.6 g. boric acid and 300 g. sulfurized oleyl alcohol containing 10.4% sulfur (prepared asin Example 1) were heated in the presence of 300 cc.

- Example 4.- Prcparation of mono-(suljurized the production of the monoester.

benzene in a reaction flask fitted with reflux condenser and .water trap. when the theoretical 4 in the table show the cumulative weight loss at the end of each four hour period.

Cumulative Bearing Weight Loss (1513.125 sq. cm.)

om 4 a 12 1o 2o 21 28 32. Hours Hours Hours Hours Hours Hours Hour! 11?, 1133" Base Oil...- 5 181 Base Dill-[4% Tri-(Sulfurized Oleyl) Borate 1 .13 I

x. Base Oil+l%Di-(Suliurized Oleyl) Borate x. 0 0 5 21 37 Base 0 +193 Mono-(Suliurized Oleyl) Borate (Ex. 4) 0 0 0 Q 0 0 12 24 39 Example 3.Preparation of di-(saljurized oleyl) borate 41.2 g. boric acid and 400 g. sulfurized oleyl alcohol containing 8.15% sulfur (prepared as described in Example 1) were heated under refluxing conditions in the presence of 250 cc. benzene in the same type of apparatus as that employed in Example 2. When an amount of water had been collected corresponding to the formation of the ell-ester, the product was treated as in Example 2. The final product after evaporation of the benzene contained 7.24% sulfur.

oleyl) borate The same general method was applied as that described in Example 2, using in this case 61 g.

boric acid, 300 g. sulfurized oleyl alcohol containing 10.4% sulfur (Example 1) and 200 cc. benzene, these amounts being those required for The product contained 9.37% sulfur.

Example 5.-Bearing corrosion test Mid-Continent bright stock. The test was conducted. as follows: 500 cc. of the oil to be tested was placed in a glass oxidation tube (13". lon and 2%" diameter) fitted at the bottom with a A" bore air inlet tube perforated to facilitate air distribution. The oxidation tube was then immersed in a heated bath so that the oil temperature was maintained at 325 F. during the test. Two quarter sections of automotive bearings of copper-lead alloy of known weight having a total area of 25 sq. cm. were attached to opposite sides of a stainless steel rod which was then immersed in the oil and rotated at 600 R. P. M., thus providing suficient agitation of the sample during the test. Air was then blown through the oil at the rate of 2 cu. ft. per hour. To increase the severity of the test, the bearings were washed and weighed at the end of each four hour period and then polished and reweighed before continuing for another period. The results given below The products of the present invention may be employed not only as the sole additives in hydrocarbon lubricatingoils but also in coniunction with such detergent type additives as metal sulfonates, metal soaps, metal phenates, metal alcoholates, metal phenol sulfonates, metal alkyl phenol sulfides, metal organo phosphates, thiophosphates, phosphites and thiophosphites, metal salicylates, metal xanthates and thioxanthates, metal thiocarbamates, reaction products of metal phenates or metal phenol sulfides with sulfur, reaction products of metal phenates ormetal phenol sulfides with phosphorus sulfides, and the like. Thus, the new additives of this invention may be used in lubricating oils containing such addition agents as nickel oleate, barium octadecylate, calcium phenyl stearate, zinc diisopropyl salicylate, aluminum naphthenate, .calcium cetyl phosphate, barium di-tert.-amyl phenol sulfide, calcium petroleum sulfonate, zinc I methylcyclohexyl thiophosphate, calcium dichlorostearate, etc.

The lubricating oil base stocks used in the compositions of this invention may be straight mineral lubricating oils, or distillates derived from paraflinic, naphthenic, asphaltic, or mixed base crudes; or, if desired, various blended oils may be employed as well as residuals, particularly those from which asphaltic constituents have been carefully removed. The oils may be refined by conventional methods using acid, alkali and/or clay or other agents such as aluminum chloride, or they may be extracted oils produced, for example, by solvent extraction with solvents of the type of phenol, sulfur dioxide, furfural, dichloroethyl ether, nitrobenzene, crotonaldehyde, etc. Hydrogenated oils or white oils may be employed as well as synthetic oils prepared, for example, by the polymerization of oleflns or by the reaction of oxides of carbon with hydrogen or by the hydrogenation of coal or its products. In certain instances, cracking coil tar fractions and coal tar or shale oil distillates may also be used. Also, for special applications, animal, vegetable or fish oils or their hydrogenated or voltolized products may be employed in admixture with mineral oils.

For the best results the base stock chosen should normally be that oil which without the new additives present gives the optimum performance in the service contemplated. However, since one advantage of the additives is that their use also makes feasible the employment of less satisfactory mineral oils or other oils, no strict rule can be laid down for the choice of the base stock. Certain essentials must of course be observed. The oil must possess the viscosity and volatility characteristics known to be required for the service contemplated. The oil must be a satisfactory solvent for the additive, although in some cases auxiliary solvent agents may be used. The lubricating oils, however they may have been produced, may vary considerably in viscosity and other properties depending upon the particular use for which they are desired, but they usually range from about 40 to 150 seconds Saybolt viscosity at 210 F. For the lubrication cording to the present invention, other agents may also be used such as dyes, pour depressors, heat thickened fatty oils, sulfurized fatty oils, organo-metallic compounds, metallic or other soaps, sludge dispersers, antioxidants, thickeners,

viscosity index improvers, oiliness agents, de-

foaming or antifoaming agents, resins, rubber, olefin polymers, voltolized fats, voltolized mineral oils, and/or voltolized waxes and colloidal solids such as graphite or zinc oxide, etc. Solvents and assisting agents, such as esters, ketones, alcohols, aldehydes, halogenated or nitrated compounds,

and the like may also be employed.

Assisting agents which are particularly desirable as plasticizers and defoaming agents are the higher alcohols having eight or more carbon atoms and preferably 12 to 20 carbon atoms. The alcohols may be saturated straight or branched chain aliphatic alcohols such as octyl alcohol (CaHnOH), lauryl alcohol (CirHnsOH), cetyl alcohol (CiaHoaOH), stearyl alcohol, sometimes referred to as octadecyl alcohol (CuHa'IOH) and the like; the corresponding olefinic alcohols such as oleyl alcohol; cyclic alcohols, such as naphthenic alcohols; and aryl substituted alkyl alcohols, for instance, phenyl octyl alcohol, or octadecyl benzyl alcohol; or mixtures of these various alcohols, which may be pure or substantially pure synthetic alcohols. One may also use mixed naturally occuring alcohols such as those found in wool fat (which is known to contain a substantial percentage of. alcohols having about 16 to 18 carbon atoms) and in sperm oil (which contains a high percentage of cetyl alcohol); and although it is preferable to isolate the alcohols from those materials, for some purposes the wool fat, sperm oil or other natural products rich-in alcohols maybe used per se. Products prepared synthetically by chemical processes may also be used, such as alcohols prepared by the oxidation of petroleum hydrocarbons, e. g., parafiln wax, petrolatum, etc.

The antioxidant additives of the present invention may be employed not only in mineral lubricating oils, but also in petroleum hydrocarbon products generally, where improved resistance to oxidation is desired. Thus, the products may be added to motor fuels, Diesel fuels, kerosene, hydrocarbon polymers, natural and synthetic rubbers, etc.

The present invention is not to be considered as limited by any of the examples described. h reassasoe having the formula:

- 6 in, which are given by way of illustration only,

but is to be limited solely by the terms of the appended claims. We claim:

1. As a new compound, an ester of boric acid 0-11 B o-n wherein R is a sulfurized. aliphatic hydrocarbon radical containing at least five carbon atoms and R is selected from the grou consisting of -H and R.

2. As a new compound, a sulfurized oleyl borate.

'3. As a new compound, mono-(sulfurized oleyl) I borate. Y

4. As a new compound, di-(sulfurized oleyl) borate.

5. As a new compound, tri-(sulfurized oleyl) borate.'.

6. A composition consisting essentially of a I mineral lubricating oil having incorporatedtherein at least an oxidation inhibiting amount of a boric acid ester having the formula:

OR B o-Jr wherein R is a sulfurized aliphatic hydrocarbon radical containing at least five carbon atoms and R is selected from the group consisting of H and R.

8. A composition'according to claim 7 in which the ester is a sulfurized oleyl borate.

9. A composition according to claim 7 in which the ester is mono- (sulfurized oleyl) borate.

10. A composition according to claim 7 in which the ester is di- (sulfurized oleyl) borate.

11. A composition according to claim 7 in which the esteris tri-(sulfurized oleyl) borate.

DILWORTH T. ROGERS. JOHN, G. McNAB.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 2,160,517 Shoemaker June 6, 1939 2,312,208 Clayton et al. Feb. 23, 1943 2,383,605 Lieber et al. Aug. 28, 1945 2,418,718 Lincoln et a1. Jan. 7, 1947 

1. AS A NEW COMPOUND, AN ESTER OF BORIC ACID HAVING THE FORMULA:
 7. A COMPOSITION CONSISTING ESSENTIALLY OF A MINERAL LUBRICATING OIL HAVING INCORPORATED THEREIN AT LEAST AN OXIDATION INHIBITING AMOUNT OF A BORIC ACID ESTER HAVING THE FORMULA: 